The invention relates to a thermal management system for a vehicle and more particularly to a powertrain thermal management system for a hybrid vehicle with provisions for passenger cabin heating and engine warm up.
A vehicle cabin heating system must be able to maintain passenger comfort at all times during operation of the vehicle, including extreme cold weather conditions. The heating system must not only be able to increase the vehicle cabin air temperature to the passenger comfort level within a reasonable amount of time of vehicle start, but also maintain the vehicle cabin temperature at the passenger comfort level.
Typically, an internal combustion engine in a conventional vehicle releases sufficient heat to adequately heat the vehicle cabin at all vehicle engine loads. The conventional vehicle uses waste heat from the engine coolant for cabin heating. However, the internal combustion engine in a hybrid electric vehicle is usually smaller than the engine in a comparably sized conventional vehicle. Also, the internal combustion engine in the hybrid electric vehicle may not be operating when the vehicle is being powered by the electric motor. Moreover, while the internal combustion engine is operating, it operates at near peak efficiency and rejects less heat to the coolant. As a -result, the heating system may not be able to provide sufficient heat continuously to the vehicle cabin to maintain passenger comfort. Additionally, upon cold start, the internal combustion engine in the hybrid electric vehicle typically takes longer to reach its optimum operating temperature than the internal combustion engine of the conventional vehicle.
It would be desirable to produce a powertrain thermal management system for a hybrid electric vehicle which provides heat to the vehicle cabin and minimizes engine warm up time.
Consistent and consonant with the present invention, a powertrain thermal management system for a hybrid electric vehicle which provides heat to the vehicle cabin and minimizes engine warm up time has surprisingly been discovered. The powertrain thermal management system for a hybrid vehicle comprises: a first cooling circuit having a first pump for circulating a coolant therein for removal of heat from a first heat source; a second cooling circuit having a second pump for circulating a coolant therein for removal of heat from a second heat source, the second heat source including at least one of an electric motor, a transmission heat exchanger, and an electronics water jacket or cold plate; a heater core for providing heat to a passenger cabin of the hybrid vehicle; and valve means in fluid communication with the first cooling circuit and the second cooling circuit, the valve means selectively routing coolant from at least one of the first cooling circuit and the second cooling circuit to the heater core.